"Scary story"?
Not really, surely it's actually evidence of the mildness of the disease.
If it's been circulating in the population for a number of weeks but has not been recognised as anything more threatening than normal seasonal flu or common cold.
I find it hard to call the disease "mild". To put it in context, IF half of the UK population are infected, a mortality of c1% of the infected half is 330,000 dead, the c5% requiring intensive care represent 1,650,000 souls, and the c20% with serious symptoms are 6.6 millions!
The nhs only has c140,000 beds in total, and few "spare" ones.
While not all infected having serious symptoms makes it harder to spot, I think the reason of failing to recognise it in the US might be due to the lack of testing, a result of being grossly unprepared.
Given thousands were tested in the UK by then, it beggars belief that for the richest nation on earth, only
445 people had been tested in the US as of 25th Feb (about a week ago) - the reason? Test kits were
only available in 3 states as of 21st Feb, and even when they were tested, kits were found to be
faulty!
Similarly, the Japanese government found it fit to test those on the Diamond Princess in dribs and drabs, and even by the end of the two week quarantine period
not all on board were tested, while in the meantime they were all essentially kept in a petri dish, infecting each other happily, resulting in c20% catching it by the end of the two weeks.
Hopefully, some valuable lessons will be learnt from these episodes.